1. Field of the Invention
This invention relates to a process for the manufacture of and optionally for the further processing of section material, suitable for the production of doors and windows, using a thermoplastic material by thermally plasticising the material and by extrusion forming said thermoplasticised matter comprising the following measures:
a) a first blending component made of thermplastic plastics waste; PA1 b) providing a second blending component with a content of additives; PA1 c) the first and the second blending component are thoroughly mixed, compacted and mixed by means of thermally plasticising of said first blending component to form a strand-forming mixture. PA1 by milling and/or glueing in the case of wood working, PA1 by extruding the plastic in the case of plastics processing, and also by extruding in the processing of light metal. PA1 d) the mixture adaptable to form strands is, under pressure, introduced in a preliminary section forming duct until the duct is completely charged, shaped to form a thick-walled preliminary section, at least partially hardened by cooling, and afterwards removed as a longitudinal part from the preliminary section forming duct with a length corresponding to the length of the preliminary section forming duct; PA1 e) the preliminary section is left to a shrinkage process for a rest time of, for example, about 5 to about 10 hours, the rest time being enough to obtain a considerable amount of the overall shrinkage to be expected; PA1 f) after this rest time the preliminary section is shaped by means of machining on at least parts of its circumference to form an intermediate section; and PA1 g) the intermediate section is coated on at least a part of its section circumference with a surface finishing layer. PA1 so that first of all the feared insufficient mechanical, and in particular the optical surface properties, are eliminated. Thus a section material is finally obtained that is at least equivalent to sections of light metal, sections of new plastics and surface-treated wood section with respect to its optical surface properties. PA1 constant pitch of 0.8 D PA1 L/D ratio 15:1 PA1 draw-in zone 3 D PA1 compression zone 7 D PA1 discharge zone 5 D, PA1 after charging a section forming duct closes the respective connecting valve; PA1 after a cooling period for cooling the mixture contained in the section forming duct, opens the proper section slide gate and the proper connecting valve; PA1 after the section, already hardened, has been partly pushed out by the mixture continuously flowing in via the connecting valve, subjects the section partly pushed out to the influence of the withdrawal device and separates it from the leading end of the refilled mixture; PA1 after the separation of the trailing end of the section and the leading end of the inflowing mixture, closes the slide gate within the thus formed separation gap and PA1 then refills the section forming duct completely until it reaches the necessary quantity for the formation of another section.
2. The Prior Art
In the traditional production of doors and windows, the legs of the sections forming the window casement and the window frame are regularly produced by machining wood. At the conclusion of the machining operation, the section legs are ready to be assembled to form window casements and window frames.
In addition, it has been known for many years to produce section material for the manufacture of window casements and window frames in the production of doors and windows made of thermoplastic plastics by extrusion. To this end the thermoplastic plastics, optionally PVC, is pressed through an extrusion die by means of a screw-type extruder, a thermoplastic state of the plastic being achieved prior to the passage through the extrusion die and the strand emerging from the die being cooled downstream of the die. The typical feature of this process is that the section material from the extrusion die that is obtained and cooled, if necessary, intermediately stored, is ready for further processing to form window casements and window frames.
It is also known to extrude section material for the manufacture of window casements and window frames from light metal. In so doing the light metal is driven through a drawing die while being subjected to cold forming. The section material obtained at the outlet of the drawing die is first cooled from the temperature attained by the heat of the forming operation to ambient temperature and is then further processed to form window casements and window frames.
It is common to all known processes that the sections are achieved in a single section forming operation
Each of these known processes has its advantages and its drawbacks.
When wood is used as a starting material solid sections are obtained, as a rule, by machining operations and are suitable for producing window casements and window frames without any reinforcing measures. The fittings for connecting window casements and window frames and any and all fittings for installing the window frames in wall openings can be attached to any location on the respective window casement and window frame by the use of wood screws or nails. The disadvantage is that the wood, even when it is thoroughly dried, exhibits considerable, long-term shrinkage which occurs at least in part after the completion of the respective window and/or respective door and even after installation into the respective wall opening, the consequence being that leakage and binding can occur between window casement and window frame, thus making subsequent adjustment necessary. In addition, plaster damage or cracks can occur in those areas where the window frames abut against the masonry. Yet another disadvantage is that the wood requires surface treatment, optionally weather-proofing, which must be repeated several times during the service life of the window casements and window frames.
The manufacture of window casements and window frames from light metals is very expensive. Window casements and window frames made of light metal are usually only used in buildings of high quality. The good thermal conductivity of light metal requires extensive measures to avoid thermal bridges and cold bridges between the exterior and the interior. The sections are as a rule produced as hollow sections, which have to be rather thin-walled, to enable an acceptable weight of the window casements and window frames. The fact that the section walls are so thin causes problems in the fastening of the fittings with the consequence that complex positive fastening solutions have to be applied when fastening the fittings, with the result that the final product becomes more expensive. It is advantageous that the windows and doors produced in such a way are weatherproof even without any particular protective measures.
The production of window casements and window frames from extruded plastic, optionally extruded PVC, is inexpensive in the original manufacture as well as during its use, since damage caused by weather is hardly to be expected. In order to reduce both the use of the material and the weight, the plastics sections are produced as relatively thin-walled hollow sections with the consequence that usually reinforcing inserts made of metal have to be inserted afterwards in the plastics sections in order to give the section the required flexural strength and the window casements and window frames the necessary torsional strength. The attaching of fittings is limited to thick-walled and multiple-walled areas as well as to areas containing metallic reinforcements. In so far as fittings are mounted on areas with metallic reinforcements, there occurs a difficulty in placing attaching screws.
A process, for extruding rods is known from the CH-A-642 901. In the process PVC waste is reused for a new production process. The moist PVC ground material is supplied to the extruder. In the PVC, ground material up to 25% by wgt of foreign substances, e.g. other plastic material, metal filings, rubber and conventional filling substances, can be contained. Substances serving the purpose of reinforcement, for example glass fibers, can be added, which may contribute to an improvement of the products of the process.
From the DE-A-1 906 012, it is known, to arrange a multiple stage die cutting instrument immediately after an extruder, in a process for the continuous production of accurate sections from thermoplastic plastics. The multiple stage die cutting instruments are passed through by the extruded section immediately after solidification and in so doing they are subsequently machined. In the process the cutting forces arising during the subsequent machining process are kept away from the forces arising during extrusion. For this purpose, the speed of withdrawing the section can be kept constant, whereas the cutting speed is adjusted independently from it. However it remains unchanged that the strand coming from the extruder passes through the multiple stage die cutting instruments undivided.